In the boardroom at his former merchant bank office in Calgary, Sonny Mottahed is taking down a black-and-white photo of the wooden derricks over Spindletop, the historic crude find that started the Texas oil boom. In its place, he’s hanging a photo of the “HOLLYWOOD” sign vandalized to read “Hollyweed,” a playful riff on the Los Angeles landmark that he hopes heralds the start of a new boom in Canada: legal marijuana. After 25 years…